//Assert
var expected = 3;
//first, can I know how many object I have the policy name "policy2".
var actual = mockSetPolicies.Object.Count(p => p.PolicyName == "policy2");
//second, can I assert the number of objects I have currently with the name "policy2".
Assert.AreEqual(expected, actual);

From there you should be able to use linq queries like Count() and it will enumerate the mock dbset.

There are also some minor modifications you need to make to allow the dbset to be enumerated effectively.

//Change this to use a Func delegate to allow multiple calls.
mockSetPolicies.As<IQueryable<Policies>>()
.Setup(m => m.GetEnumerator())
.Returns(() => policyData.GetEnumerator());
//Set this up to return a new model if it is being used.
mockSetPolicies
.Setup(x => x.Create<Policies>())
.Returns(() => new Policies());

Assuming the service exposes a property that allows access to the dbset you can assert the count there or via the mock it self.